1. Technical Field
The present invention relates to semiconductor technology, and more particularly, to a polishing material for chemical mechanical planarization of a thin film and a chemical mechanical planarization method using the same.
2. Related Art
In recent years, with increase in demand for portable digital devices such as digital cameras, MP3 players, personal digital assistants (PDAs), and portable phones, the nonvolatile memory market is rapidly expanding. As flash memory devices, which are programmable nonvolatile memory devices, reach the limit of scaling, nonvolatile memory devices such as phase-change random access memory (PcRAM) devices or resistive random access memory (ReRAM) devices using a variable resistor with a reversibly changeable resistance value have received attention as an alternative to the flash memory devices. Since the nonvolatile memory devices use a physical property of the variable resistor itself as a data state, a configuration of a cell can be simplified so that miniaturization of the memory device can be realized.
A resistance value of chalcogenide materials, such as a germanium (Ge)-antimony (Sb)-tellurium (Te) alloy, may be changed according to a material phase or an intensity or width of an applied electrical signal. Thus, chalcogenides have been widely studied as candidate materials for the above-described non-volatile memory devices. In non-volatile memory devices, the chalcogenide material may be formed with a damascene process in which the chalcogenide material is buried in holes formed in an interlayer insulating layer. Chemical mechanical polishing (CMP) may be used as a planarization method in the damascene process.
A CMP process may be optimized for the material that is being removed. Existing processes are optimized for copper and aluminum. Since chalcogenide materials include metal compounds with two or more different elements, it may be helpful to develop a new process for chalcogenide materials. Further, when a chalcogenide material is formed in a damascene structure, since the chalcogenide material may be formed in a cell pitch of below 20 nm to enhance the integration density, a low surface profile and low defect level in a polishing surface have to be ensured. CMP characteristics that are desirable to be optimized include uniformity and polishing speed. CMP techniques for chalcogenide materials may also be applied to a metal oxide material containing two or more different kinds of metal or metalloid elements, for example, Perovskite-based metallic compound such as PbZrxTi1−xO3.